Coupling or lock between two sheets of different materials such as carton and plastic

ABSTRACT

A coupling or lock connecting a first carton or plastic sheet part with a second plastic sheet part. The first part has a Ushaped slit to form a locking tongue and the second part has a recess having one end open to receive the locking tongue. The opposite end and side walls of the second part from abutments for the end edge and side edges of the locking tongue. The recess provided in one side of the second part forms a projection on the opposite side of the second part. The opening formed by the slit defining the locking tongue is moved over the projection so that the walls of the recess will be clamped between the edges of the opening and the corresponding edges of the locking tongue.

United States Patent 1191 1111 3,809,305

Persson May 7, 1974 1 COUPLING OR LOCK BETWEEN TWO 2,531,066 11/1950 Lynch 220/31 s x SHEETS OF DIFFERENT MATERIALS SUCH 2,746,081 5/ 1956 Gershen 220/31 S AS CARTON AND PLASTIC [75] Inventor: Karl Rune Persson, Halmstad,

Sweden [73] Assignee: Sprinter Pack AB, Halmstad,

Sweden [22] Filed: Nov. 1, 1972 [21] Appl. No.: 302,802

[30] Foreign Application Priority Data Nov. 1, 1971 Switzerland ..l3930 [52] U.S. Cl... 229/45, 220/60 [51] Int. Cl B65d 45/14 [58] Field of Search 229/44, 45; 220/31 S, 60

[56] References Cited UNITED STATES PATENTS 2,628,012 2/1953 Goldsholl 229/44 R 3,122,299' 2/1964 Haas 239/44 R X 1,681,032 ,8/1928 Fuller 220/31 S 2,474,311 6/1949 Graham 220/31 S 2,583,350 1/1952 Witzgall 220/31 S 2,243,065 5/1941 Barrett 220/31 S Primary Examiner-William 1. Price Assistant Examiner-Douglas B. Farrow Attorney, Agent, or Firm-Ostrolenk, Faber, Gerb & Soffen [57] ABSTRACT A coupling or lock connecting a first carton or plastic sheet part with a second plastic sheet part. The first part has a U-shaped slit to form a locking tongue and the second part has a recess having one end open to receive the locking tongue. The opposite end and side walls of the second part from abutments for the end edge and side edges of the locking tongue. The recess provided in one side of the second part forms a projection on the opposite side of the second part. The opening formed by the slit defining the locking tongue is moved over the projection so that the walls of the recess will be clamped between the edges of the opening and the corresponding edges of the locking tongue.

10 Claims, 10 Drawing Figures PATENTEDIAY 7 19 14 SHEET 1 If 2 PATENTEDm H914 SHEET 2 [IF 2 COUPLING OR LOCK BETWEEN TWO SHEETS OF DIFFERENT MATERIALS SUCH AS CARTON AND PLASTIC The present invention relates to a coupling or lock of the kind referred to in the opening paragraph of the accompanying claim 1.

The object of the invention is to provide a simple coupling or lock which is easy to use for connecting a relatively stiff plastic sheet and a piece of carton. Primarily, the invention is intended to provide a releasable interconnection of a lid and a tray. The tray may consist of a plastic sheet formed under heat and which may be easily formed with partition walls separatingcompartments whereas the lid consists of a piece of carton. The plastic tray may for example be used for readymade food and in such a case it is important that the bottom of the tray and walls are tight. For this reason it would not be suitable to use a conventional lock of the kind where one part of the lock is provided with a locking tongue and the other part has a slit for receiving the locking tongue. Due to the fact that it is desired to have a substantially completely liquid-tight tray, it is undesirable to provide slits in the walls of the tray for receiving a locking tongue from the lid. Therefore, an object of the invention is to provide a coupling or lock in which one part is provided with a locking tongue which can be connected with the other part while eliminating the need for providing the said other part with a slit.

This is made possible by employing a coupling or lock of the kind defined in the accompanying claims. A plastic sheet part has a recess in its one side for receiving a locking tongue which is partially cut out in the carton part in the form of a U-shaped slit. At its opposite side the plastic sheet part has a projection which is intended to be engaged by one edge of the opening in the carton part which opening corresponds to the locking tongue.

Embodiments of the coupling or lock according to the invention will be described in the following with reference to the accompanying drawings.

before effecting the lock in the way illustrated in FIGS. 5 and 6,

FIG. 8 is a view similar to FIG. 7 and illustrates a modified embodiment of the invention,

FIGS. 9 and 10 are sectional views along the lines 9-9 and l0--l0, respectively of FIG. 8.

In FIGS. 1-6 are shown a carton part 10 and a plastic sheet part 12. The plastic sheet part may be formed under heat according to known methods and has been shaped with a recess 14 in one of its sides which is referred to as the upper side of the plastic sheet part.

The recess 14 has one of its ends adjacent one edge 16 of the plastic sheet part and this edge is referred to as the side edge. Further, the recess has a bottom 18 which is inclined downwardly and extends to an end wall 20 of the recess. The end wall is convex adjacent the bottom 18 so that the outer side of the end wall will form a hook-like projection 22.

The side walls of the recess have the shape of wedges and are denoted by numeral 24.

In the carton part 10 is cut out a U-shaped slit 26,27,28 to define a locking tongue 30. The lockingtongue is substantially rectangular and may be raised by bending along an imaginary or real fold line 32.

At the fold line 32 are small slits 34 for defining two edge portions 36 of the locking tongue 30. These edge portions may be folded along fold lines 38,40 and have a length which is somewhat shorter than the maximum FIG. 1 is a plan view of acarton part provided with a locking tongue,

FIG. 2 shows a plastic sheet part formed with a recess in its one side for enabling a connection with the locking tongue inFIG. 1,

FIG. 3 is a section through the locking tongue along line 3-3 in FIG. 1,

FIG. 4 is a section through the recess along line 4-4 in FIG. 2,

FIG. 5 is a broken perspective view of the locking tongue in its locked position in the recess, this view being seen obliquely from above towards the locking tongue,

FIG. 6 is a corresponding broken perspective view of the coupling as in FIG. 5, the two parts of the coupling being shown in an inverted position to show the engagement of the hook-like projection at the underside of the plastic sheet part which projection is obtained due to the recess in the upper side of the plastic sheet part, 1

FIG. 7 shows diagrammatically a tray of plastic sheet material and a carton lid to be connected with the tray, the lid and the tray being provided with two couplings or locks according to the invention shown in a position length of the locking tongue from the fold line 32 to the end edge 42 of the locking tongue.

The U-shaped slit 27 will define the edges of a corresponding opening in the carton part 10 and this opening is defined by two side portions 44 and 46 and a transverse portion 48 between the side portions 44,46. Thus, a U-shaped locking member is obtained which can be used for locking as described below.

For coupling parts 10 and 12 the locking tongue 30 is bent up from the part 10. Thereafter, the locking tongue is moved into the recess 18 of the plastic part 12 and at the same time the locking member portions 44,46,48 are moved under the plastic part 12. When the end edge 42 of the locking tongue 30 abuts the end wall 20 of the recess, the locking member 44,46,48 is bent towards the underside of the plastic part 12, and the opening 27 will then pass around the outer side of the recess. The transverse edge of the locking member will snap over the projection 22 so that the locking tongue 30 will press against the inside of the end wall 20, with the transverse end edge of the locking member simultaneously pressing against the outer side of the end wall 20. When securing the locking member 44,46,48 in this way, there is obtained a deformation of the small corner portions 50,52 at the ends of the transverse edge of the locking member. These corner portions 50,52 are clearly shown in FIG. 1. Because of this deformation there is obtained an additional strong friction locking of the locking member 44,46,48 on the projection 22 which furthermore is hook-shaped in order to obtain a still more reliable locking action.

As will be seen from FIG. 5, the side portions 36 of the locking tongue are bent upwardly somewhat along the side walls 24 of the recess. This bending of the side portions 36 will result in a reinforcement of the locking tongue so that the possibility of bending the same will be reduced when the locking tongue is pressed against the wall 20 of the recess when the U-shaped locking member 44,46,48 has engaged the hook-like projection 22.

FIG. 7 shows a pair of couplings according to FIGS. 1 to 6 used for connecting'a plastic sheet tray 54 with a carton lid 56. One side 58 of the tray has recesses 18 of the same shape as shown in FIGS. 2 and 4, and the upper edge 60 of this side 58 corresponds to the side edge 16 in FIG. 2. The lid 56 is provided with a bendable edge flap 62 which may be bent along a fold line 64 corresponding to the fold line 32 in FIG. 1.

In theflap 62 are slits to define two locking tongues 30 of the'same configuration as shown in FIGS. 1 to 6. The lid is connected with the side wall 58 of the tray by means of the two couplings or locks shown in the Figure in the same way as described in connection with FIGS. and 6.

In FIGS. 8 and 9 are shown a portion of a carton lid 56a and a portion of a plastic sheet tray with a bottom 54a in spaced relation. The side wall 58a of the plastic sheet tray is formed with two recesses 66 for receiving corresponding locking tongues 79 in the lid. Only the left hand locking tongue 79 is shown for simplicity.

. From FIG. 8 and the section in FIG. 9 taken along line 9-9 in FIG. 8, it will be understood that the recess in one side of the plastic sheet wall 58a will result in a corresponding projection 70 at the opposite side of the wall as seen in FIG. 9. The side .edges 72, 74 of the recess 66 and the side edges 76,78 of the FIG. 8 converge towards the bottom 80 of the recess 66.

As will be understood from the Figures, the side walls of the recess are provided with grooves 82,84 for receiving corresponding edges 76,78 of the locking tongue 79. The bottom 80 of the recess is somewhat inclined FIG. to receive the corresponding end edge 81 of the locking tongue.

As in FIGS. 1-6, the locking tongue 79 is defined by a U-shaped slit which also defines a corresponding opening in the carton part. The transverse edge 88 of the opening will form a locking edge of a portion 62a when the locking tongue 79 has been inserted into the recess 66 with its side edges 76,78 engaging the side grooves 82,84 and its end edge 81 rests against the bottom 80 of the recess 66. The locking edge 88 of the opening is then finally snapped over the bottom 80 of the projection 70 to to lock the locking tongue in the recess. Small tabs 90 at both sides of the locking tongue will then be deformed against the edge 60 of the side wall 58a and provide a resilient pressure tending to keep the locking edge 88 in engagement with the underside of the bottom 80.

In the two embodiments disclosed, the tongue and purposes of 79 will be held in locked position by cooperation of its edges with the side and end walls of the recess l8 and 66, respectively. Since these walls of the recess will be clamped between the edges of the tongue and corresponding edges in the U-shaped opening formed by a slit, the friction forces thus obtained will effectively retain the lockingtongue in its locked position.

What is claimed is:

1. A coupling or lock connecting a first member or part of carton, plastic sheet material or similar pliable .material with a second member or part of plastic sheet material which has a side edge, characterized in that the plastic sheet or second part has a recess in one side referred to as its upper side and a corresponding projection on its underside, that the recess has one end lohaving two side edges and a free end edge, that the edges of the opening which corresponds to the locking tongue form the inner edges of a locking member with a transverse edge which corresponds to the transverse edge of the locking tongue and forms a coupling edge, that the locking tongue is bent to a position in which its end edge is above the opening in the carton part and is inserted into the recess in the upper side of the plastic sheet part with its end edge resting against the inside of the end wall of the recess, that the portion of the carton part which is provided with the opening and forms the locking member is inserted under the underside of the plastic sheet part, and that the coupling edge ofthe opening is in engagement with that edge of the projection which is formed by the outer side of the end wall of the recess so that at least part of the end edge of the locking tongue is pressed against the inside of the end wall and at least part of the coupling edge of the opening is pressed against the outer side of the end wall in order to connect the carton part or a corresponding member with the plastic sheet part.

2. A coupling according to claim 1, characterized in that the end wall of the recess is formed with a groove for forming a corresponding hook-like projection at the outer side of the end wall for receiving and securing the coupling edge of the opening.

3. A coupling according to claim 1, characterized in that the locking tongue fits into the recess and is guided aginst its side walls, and that the side edges of the opening are guided aginst the outside of the side walls of the recess.

4. A coupling according to claim 3, characterized in that the side edge portions of the locking tongue are bent along the side walls of the recess.

5. A coupling according to claim 4, characterized in that the slit is at the end edge of the locking tongue formed with recessed corner portions at the ends of the coupling edge of the opening .so that the corner portions are deformed when snapping to the locking position against the outer side of the end wall of the recess.

6. A coupling according to claim 5 for connecting a lid with one side of a tray, characterized in that one of the parts of the coupling forms a portion of a lid and that the other part of the coupling forms part of a tray.

7. A coupling according to claim 6, characterized in that the tray is formed by a plastic sheet and is at its one side wall provded with at least two mutually spaced re-' cesses whereas the lid is provided with corresponding locking tongues and corresponding openings witha coupling edge to be connected with the tray.

8. A coupling according to claim 7, characterized in that the distance between the end wall of the recess and the side edge is about equal to thelength of the tongue between its end edge and a line between the inner ends of its side edges.

9. A coupling according to claim 1, characterized in that the side walls of the recess are formed with grooves for guiding the side edges of the locking tongue.

10. A coupling according to claim 9, characterized in that the side walls of the recess and the side edges of the locking tongue converge towards the end wall of the recess and the end edge of the locking tongue, respectively. 

1. A coupling or lock connecting a first member or part of carton, plastic sheet material or similar pliable material with a second member or part of plastic sheet material which has a side edge, characterized in that the plastic sheet or second part has a recess in one side referred to as its upper side and a corresponding projection on its underside, that the recess has one end located at the edge of the plastic sheet part and an opposite end which is defined by an end wall of the recess, that said end wall is preferably parallel to the edge of the plastic sheet part, that the first member or carton part is provided with a slit extending substantially in the form of a U to define a corresponding locking tongue having two side edges and a free end edge, that the edges of the opening which corresponds to the locking tongue form the inner edges of a locking member with a transverse edge which corresponds to the transverse edge of the locking tongue and forMs a coupling edge, that the locking tongue is bent to a position in which its end edge is above the opening in the carton part and is inserted into the recess in the upper side of the plastic sheet part with its end edge resting against the inside of the end wall of the recess, that the portion of the carton part which is provided with the opening and forms the locking member is inserted under the underside of the plastic sheet part, and that the coupling edge of the opening is in engagement with that edge of the projection which is formed by the outer side of the end wall of the recess so that at least part of the end edge of the locking tongue is pressed against the inside of the end wall and at least part of the coupling edge of the opening is pressed against the outer side of the end wall in order to connect the carton part or a corresponding member with the plastic sheet part.
 2. A coupling according to claim 1, characterized in that the end wall of the recess is formed with a groove for forming a corresponding hook-like projection at the outer side of the end wall for receiving and securing the coupling edge of the opening.
 3. A coupling according to claim 1, characterized in that the locking tongue fits into the recess and is guided aginst its side walls, and that the side edges of the opening are guided aginst the outside of the side walls of the recess.
 4. A coupling according to claim 3, characterized in that the side edge portions of the locking tongue are bent along the side walls of the recess.
 5. A coupling according to claim 4, characterized in that the slit is at the end edge of the locking tongue formed with recessed corner portions at the ends of the coupling edge of the opening so that the corner portions are deformed when snapping to the locking position against the outer side of the end wall of the recess.
 6. A coupling according to claim 5 for connecting a lid with one side of a tray, characterized in that one of the parts of the coupling forms a portion of a lid and that the other part of the coupling forms part of a tray.
 7. A coupling according to claim 6, characterized in that the tray is formed by a plastic sheet and is at its one side wall provded with at least two mutually spaced recesses whereas the lid is provided with corresponding locking tongues and corresponding openings with a coupling edge to be connected with the tray.
 8. A coupling according to claim 7, characterized in that the distance between the end wall of the recess and the side edge is about equal to the length of the tongue between its end edge and a line between the inner ends of its side edges.
 9. A coupling according to claim 1, characterized in that the side walls of the recess are formed with grooves for guiding the side edges of the locking tongue.
 10. A coupling according to claim 9, characterized in that the side walls of the recess and the side edges of the locking tongue converge towards the end wall of the recess and the end edge of the locking tongue, respectively. 